Macrophage Inflammatory Protein 4 (MIP-4), also known as CCL18, is a chemokine expressed in the lymph nodes, lungs, placenta, and bone marrow. MIP-4 receptors include the chemokine receptor 8 (CCR8), the G protein-coupled receptor 30 (GPR30), and the phosphatidylinositol transfer protein membrane-associate 3 (PITPNM3). MIP-4 acts as a chemoattractant for naive T cells, CD4+ T cells, CD8+ T cells, and nonactivated lymphocytes. Further, MIP-4 promotes breast cancer metastasis and attenuates the activation of acute lymphocytic leukemia B cells.